1. Field of the Invention
This invention pertains generally to electrical power devices and more particularly to an apparatus for cooling electrical power devices.
2. Description of the Related Art
The power rating of present-day electrical devices, such as power transformers and motors, is limited by heat accumulation due to resistive losses in the copper windings and, in the case of power transformers, to losses from eddy currents and hysteresis within the iron or ferrite cores. It is not generally recognized that the magnetic flux within a transformer core remains approximately constant when the power output is increased. It is therefore unnecessary to increase the amount of iron or ferrite core material to increase the size of the transformer core in order to deliver more power. The trapped heat produced by the windings while operating at high power is the major limiting factor for high power transformers.
Different approaches have been attempted to try and remove heat from the core of power transformers. Some of these are the increasing of wire size to reduce resistive losses; immersion of the transformer in circulating coolant oil; air cooling of the transformer windings; increasing the operating frequency of the transformer to reduce windings; and increasing the thermal conductivity of the insulating potting compound around the transformer windings. All of these, however, impact on the mechanical size and weight of the transformer designs limiting the use of these applications. Without proper cooling the efficiency and reliability of these transformers and motors are considerably reduced.
The object of this invention is to provide an apparatus for cooling high power electrical devices.
Another object of this invention is to provide a cooler operating high power electrical device that is of light weight, low cost, higher power density, and highly efficient design.
These and other objectives are obtained by placing thermal conductive strips between the turn layers along the axis and perpendicular to the turns of an high power electrical device, such as a transformer or motor, which extends outside of the windings or between the laminates of the core. The excess heat is conducted outward from the interior of the device along the strips to the outside of the device""s windings where it is extracted from the protrusions by means of a highly thermal-conductive potting compound that has a short thermal path to a small heat sink.